Conventionally, a plasma process is utilized for manufacturing semiconductors and electronic devices or for surface modification of structural materials. Examples of these kinds of plasma processes include ion beam etching and ion beam sputtering. Ion beam etching is the etching process of extracting ions from plasma in the form of a beam and then irradiating a metal film on the surface of a substrate to be processed with the ions. The ion beam sputtering is the sputtering process of extracting ions from plasma in the form of a beam, irradiating a sputtering target with the ion beam, and then depositing the sputtered materials onto a substrate to be processed.
Several ion sources, such as capacitive coupling type, inductive coupling type (ICP type) and electron cyclotron resonance type (ECR type), are known as the plasma processing apparatus mentioned above. As shown in FIG. 16, the ion source of the inductive coupling type includes a plasma generating chamber 1, a partition wall 2 made of a dielectric material and partitioning the plasma generating chamber 1, and a high-frequency antenna 3 arranged externally of the partition wall 2 for generating plasma in the plasma generating chamber 1.
The partition wall 2 is typically made of a dielectric material such as quartz. As shown in FIG. 16, the high-frequency antenna 3 is a coiled shape disposed around the periphery of the partition wall 2 and generates inductively coupled plasma through the partition wall 2. Only ions 7 are accelerated by extraction electrodes 4 from the plasma and are extracted to a process chamber 5. An object matter 6 such as a substrate or a sputtering target is irradiated with the extracted ions 7 and then the predetermined etching process or deposition process is carried out.
In the above conventional ICP type ion source, the object matter 6 is sputtered by the ions extracted from plasma and parts of sputtered materials 8 adhere onto the inner surface of the partition wall 2 partitioning the plasma generating chamber 1. Particularly when the sputtered materials 8 are made of a conductive material and are deposited onto the inner surface of the partition wall 2 in the winding direction of the high-frequency antenna 3 in succession, a current flows to the inside surface of the partition wall 2 in a direction denying an induction electromagnetic field produced in the plasma generating chamber 1. As a result, a dielectric loss is increased. Also, conductive sputtered materials 9 from the extraction electrodes 4, which are generated by collision of ions 7 on the electrodes 4, may adhere onto the inner surface of the partition wall 2 through the plasma generating chamber 1.
As described above, when the conductive materials adhere on the inner peripheral surface of the partition wall 2 around the whole periphery thereof, the dielectric loss is increased and also high-frequency power for obtaining a desired plasma density is increased, thereby finally causing the problem of difficulty in stable formation or maintenance of plasma.
To solve the problem, Patent Documents 1 and 2 disclose a construction in which a shield body for regulating the adhesion of sputtered materials onto the inner surface of a partition wall is installed inside a plasma generating chamber. The shield body is installed opposed to the inner surface of the partition wall. Thus, sputtered materials are restrained from adhering to the inner surface of the partition wall, and then a stable generation or maintenance of plasma is secured.    Patent Document 1: JP2004-228181A    Patent Document 2: JP11-251303A